Purpose: Mixed beam radiation therapy (MBRT) has been shown by many investigators to be a promising modality. In our institution, we have developed an in-house Monte Carlo based treatment planning system for MBRT treatment planning. The aim of the current work is to develop a graphic user interface (GUI) for this system and to promote its clinical application.

Methods: We have used the MCBEAM code for treatment head simulation and for generating phase space files to be used as radiation source input for our treatment planning system. The MCPLAN code was used as a Monte Carlo dose calculation engine. An interface was constructed to facilitate the input of all required parameters for the planning process. The planner can also input all Monte Carlo simulation parameters or simply use the default values already stored in the program. A display window interface was developed to show the virtual patient phantom and the planner can easily explore the different patient transversal CT cuts by using a scroll bar. The planner could then place the beams after mouse clicking to select the target isocenter. The planner could visually change the beam angles. The virtual phantom is generated using another interface, named MCDICOM. MCDICOM was developed for creating a virtual phantom with 3D rectilinear voxel geometry for Monte Carlo dose calculation based on DICOM-compatible export from other treatment planning system.

Results: The GUI for MBRT treatment planning provided a great tool for gantry angle selection. It streamlines the treatment planning process by integrating all seperate codes into one running environment. The GUI interface improved the operation efficiency for our in-house treatment planning system.

Conclusion:Our GUI based program can facilitate the clinical implementation of MBRT and its widespread clinical applications.

Funding Support, Disclosures, and Conflict of Interest: This work has been supported by a UICC American Cancer Society Beginning Investigators Fellowship funded by the American Cancer Society